Kevin starts counting at 24, and he counts by threes. If 24 is the 1st number that Kevin counts. what is the 15th number that he counts?
Solution: What is the first number that he counts? $24$ What is the second number that he counts? $\begin{align*}&24 + 3 \\ &= 27\end{align*}$ What is the third number that he counts? $\begin{align*}&24 + 3 + 3 \\ &= 24 + (2 \times 3) \\ &= 30\end{align*}$ What is the 15th number that he counts? $\begin{align*}&24 + (14\times3) \\ &= 24 + 42 \\ &= 66\end{align*}$